Partial Discharge On-line UHF Monitoring System Based On Virtual Instruments Technology For GIS

With the development of the society,the requirement for the quality of power supply is more and more higher. So gas insulated switchgear(GIS) has more and more applications in the power system due to its characteristics advantage, such as small volume, high quality, etc. Operation experiences show that intrinsic defects in GIS still cause accidents though its high reliability. Insulation breakdown is primary reason for GIS electrical failures. Partial discharge (PD) phenomena are the most common characteristic before insulation breakdown in GIS. By PD on-line monitoring systems, GIS internal defects can be discovered in time to avoid the occurrence of fatal failure.In this paper, a partial discharge on-line ultra high frequency (UHF) monitoring system based on Virtual Instruments Technology for GIS is proposed. The part of hardware designed in the paper includes the multiplex switch, amplifier and filter. Moreover, the UHF microstrip antenna and digital I/O module and data acquisition unit---TDS5032 digital oscilloscope were selected according to the requirements of system. The software of system was developed based on Virtual Instruments (VI) technology, which can realize hardware configuration, data acquisition, partial discharge waveform display. In addition, the system can also give the maximum discharge quantity, the alarm for equipment occurred PD, and the data analysis software including filter analysis, spectrum analysis, wavelet analysis and JTFA analysis. The history data can be stored automatically and real time. Moreover, the developing trend of discharge parameters can be queried and analyzed for the condition evaluation of insulation.The installation scheme is designed based on the practical situation of GIS substation, and then the system is installed and brought into service in laboratory. the results show that the system is stable and effective, and it could run continuously, reflect the GIS condition actually and find the condition trouble in time. So it is very significant to improve the GIS reliability and security by such system.